Question

Find the center and radius of the circle.

Answer 1

Hello from MrBillDoesMath!

Answer:

Center = (-4,3)

radius = 4

Discussion:

x^2 + y^2 + 8x -6y + 9 = 0

Let "complete the square" for the x and y terms:

x^2 + y^2 + 8x -6y + 9 = 0  =>                     group like terms

(x^2 + 8x ) + (y^2 - 6y) + 9 = 0 =>                complete the square for x, y

(x^2 + 8x + 16) + ( y^2 - 6y + 9) -16 - 9 +9 = 0  =>

(x+4)^2 + ( y-3)^2 = 16 + 9 - 9 =>

(x+4)^2 + ( y-3)^2 = 16  =>

Therefore,

radius = sqrt(16) = 4,

Center = (-4,3)

Graph of function attached.

Thank you,

MrB